Semiconductor integrated circuits utilizing high impedance transistor technologies such as metal oxide semiconductor (MOS) technologies are known to be vulnerable to ESD. ESD “events” may include the so-called “human body model” (HBM) type of event. See e.g., JEDEC Standard JS-001-2012, JOINT JEDEC/ESDA STANDARD FOR ELECTROSTATIC DISCHARGE SENSITIVITY TEST—HUMAN BODY MODEL (HBM)—COMPONENT LEVEL (2012) for additional information about HBM. A person may accumulate static electrical charge on the surface of his or her body, generally through the rubbing together of dissimilar articles of clothing, shoes rubbing against carpet, clothing rubbing against a car seat when entering or exiting a vehicle, etc., particularly at times of low relative humidity. An HBM ESD event occurs when the person subsequently touches a conductor, including perhaps an electronic circuit and discharges the accumulated charge to and through circuit components. Such components may be subject to damage by a resulting discharge pulse of 1000 volts or more with a discharge time of several hundred nanoseconds.
ESD protection devices utilizing a metal oxide semiconductor field-effect transistor (MOSFET) as a discharge device between voltage rails are known. A MOSFET designed for such purpose typically includes a wide, short current channel able to conduct several amperes of current produced by a typical ESD event. Existing ESD protection devices may be subject to false triggering during power supply startup and/or as a consequence of power supply glitches during operation.